I'm a little over a week and half out from my 2nd DAT. I didn't really start studying hard core for this one until two months ago... But, this is what I've been doing and I've seen a dramatic improvement in my memory of biology and chemistry.
For biology, I made notes on a half sheet of paper of things I would not remember or just notes in general. So every couple of nights I go back and reread my outlines. What I studied from was the Campbell text book, the AP Cliffs bio book, and the Kaplan white book. Great sources! And of course I pulled notes from my old notebooks from college. (I've been out for over two years).
For Chemistry, the key is to PRACTICE. I've done problems from the kaplan blue and white books, Examcrackers 1001 chem book (I know it's MCAT but i'm trying to get my hands on enough chem problems b/c it was my lowest score on the last DAT) and top score. I'm even thinking about getting the AP Cliffs chem book just to do more practice in the next week leading up to my test. But PRACTICE!
For Organic... the same as biology. Just remember concepts and reactions and you're golden. On my first DAT it was very straightforward. It was one of my highest scores besides my PAT and RC.
PAT... CDP 👍... I can't stress how wonderful it is. I used it for my first time around and did well on the PAT... and i'm reusing it for this DAT and my scores have jumped up higher! (I also think it comes with training my brain to be more aware of details).
RC... I read a lot so I'm not worried and I scored a 20 without practicing on my last DAT... but a trick is write key words down from the passage. It makes your life a lot easier when you answer questions.
QR is a pain. I had to pull out my old pre-cal notebook from college to relearn trig. I'm also using the GRE math book to practice.
Anyway... I know this is long but I hope it helps you! Good luck! 😀